Lower Permian Limestones of Southern New Mexico and West Texas: ABSTRACT

Abstract

Detailed petrographic and stratigraphic analyses of samples from the Lower Permian (Wolfcampian) of southern New Mexico and West Texas demonstrate the effects of major tectonic elements on redbed and carbonate sedimentation. Regional correlations are based on 3 informal stages (upper, middle, and lower Wolfcampian), as determined by fusulinid zonation. Uplifted areas, such as the Pedernal landmass, Diablo platform, and the Florida islands, display unconformable surfaces, limestone and chert conglomerates, and shallow-water carbonates facies consisting of foraminiferal-algal packstones and grainstones (shoal water), algal plate wackestones (bioherm), and ostracod-molluscan packstones and wackestones (lagoon). These highs were flanked by carbonate shelf deposits of normal marine wackestones and packstones which rim the Orogrande and Pedregosa basins. The former was a shallow water intracratonic basin in which about 2,000 ft of Wolfcampian sediments accumulated. The latter basin is less understood, but had a well-defined shelf margin and received at least 4,000 ft of Wolfcampian sediments. Distant uplifts on the north of the Orogrande basin shed thick redbed deposits which intertongued with carbonates on the south. Generally, this resulted in 3 major sedimentary phases (2 carbonate phases separated by a redbed phase) which correspond to the original threefold division of the type Hueco Limestone. This interpretation together with fusulinid zonation permits correlation of stratigraphic units of southeastern Arizona with those of West Texas and New Mexico: youngest Horquilla Limestone with Hueco Canyon Formation, Earp Formation with Abo Redbeds and Cerro Alto Limestone, and Colina Limestone with Alacran Mountain Formation. End_of_Article - Last_Page 631------------